A catheter for use in a patient's heart, especially for mapping a tubular region of the heart, has a catheter body, a deflectable intermediate section and a distal mapping assembly that has a generally circular portion adapted to sit on or in a tubular region of the heart. A control handle of the catheter allows for single-handed manipulation of various control mechanisms that can deflect the intermediate section and contract the mapping assembly by means of a deflection control assembly and a rotational control assembly. The deflection control assembly has a deflection arm and a rocker member. The rotational control assembly has an outer rotational member, an inner rotational member and a cam. A pair of puller members are responsive to the deflection control assembly to bi-directionally deflect the intermediate section. A third puller member is responsive to the rotational control assembly to contract the generally circular portion of the mapping assembly.